Recent years have witnessed ever increasing quantities of carbonated beverages, such as beer and carbonated soft drinks, being packaged in amounts up to 12 ounces in metal cans and particularly in metal cans with end closures that include a score line defined opening panel therein to provide implement free access to the contents. Such opening panel containing can ends are generally called "easy open ends" and include variant basic constructions of a first type wherein the score line completely circumscribes the panel to render the panel completely separable from the can end and of a second type wherein the score line only partially circumscribes the panel to render the latter only partially severable from the can end and to thus remain in attached relation within the can end after the pouring opening has been formed. As mentioned above, such opening panels are conventionally perimetrically delineated by score lines of decreased metal thickness.
In order to extend the use of such easy open can end constructions to larger volume containers, the art has suggested the utilization of a cap assembly to close and reseal the opening defined by such score line defined panel. Among the objects of such cap utilization are a re-closure of the container to prevent loss of liquid content and a resealing of the container to limit further losses of the dissociable gases, i.e., the "carbonation", of the remaining liquid contents. U.S. Pat. No. 4,580,692discloses one construction for such a resealable closure cap assembly in association with a selectively contoured can end construction to cooperatively accommodate such resealable closure and to retain the advantages characteristic of the "easy open end" construction.
The provision of commercially acceptable resealable easy open can end constructions for larger capacity beverage containers requires, in addition to the functional feature of present easy open can ends, both sealable retention of the can contents and accommodation by the resealed cap of the inherent pressure buildup therein. Also required is a can end configuration at the pouring opening to accommodate the disposition of the resealing cap in operative relation thereto without appreciable diminution of the convenience and cost effective nature of the basic easy open end constructions during manufacture, filling, shipping, selling, and consumer usage. As such, the provision of a commercially acceptable resealable easy open end construction requires accommodation of problems not heretofore met in the basic easy open end constructions conventionally employed in the smaller capacity beverage can.
Experience to date with the resealable cap and can end construction disclosed in U.S. Pat. Nos. 4,580,692 and 4,648,528, the disclosure contents of which are herein generally incorporated by reference, has indicated that a pressure buildup within a resealed can in excess of about 20 psi, a not uncommon occurrence, may result in a reverse displacement of the opening panel, i.e., from the inside to outside of the can, due to rapid pressure release occasioned by separation, intended or otherwise, of the resealing cap from the pouring spout. Such reverse displacement of the opening panel and consequent exposure thereof externally of the can interferes with pouring and resealing, which motivates the user to take corrective action, thereby creating a possible cutting hazard to the user if he attempts either to remove the panel or to force it back into the can and, if separated and discarded by the user, creates an undesirable littering potential.